1. Field of the Invention
The present invention relates to an optometry apparatus for performing a subjective examination including: indicating various indices to a person to be examined; and obtaining an eyesight value of an eye to be examined based on appearance states of the indices.
2. Description of the Related Art
Up to now, subjective examinations have been widely performed in ophthalmologic fields, spectacle stores, and the like. In the subjective examinations, indices such as Landolt rings for eyesight measurement and fan charts for astigmatic measurement are indicated to a person to be examined and an eyesight value of an eye to be examined is obtained based on appearance states of the indices. In conventional subjective examinations, an examiner asks the person to be examined question about the appearance states of the indices. The examiner performs the selection of a next index to be indicated and the determination of the eyesight value based on the reply of the person to be examined.
In recent years, there has been proposed an optometry apparatus capable of performing both an objective examination for optically measuring the spherical power and cylindrical power of the eye to be examined and the above-mentioned subjective examination and attention has been given thereto. A structural example of such an optometry apparatus is disclosed in JP 2002-119476 A (claim 6, specification paragraphs [0039] to [0043]). The optometry apparatus includes an automatic alignment mechanism for automatically aligning an optometry unit with the eye to be examined, a manual alignment mechanism for manually aligning the optometry unit with the eye to be examined by a person to be examined, a determination unit for determining whether or not automatic alignment can be performed, and an informing unit for giving an explanation about the automatic alignment to the person to be examined to understand it.
An optometry system is disclosed in JP 2002-119471 A (claims 1 and 2, specification paragraphs [0023], [0038] to [0040], [0042] to [0044], and [0055] to [0058], and FIGS. 4 to 7). The optometry system includes a monitor for displaying an optometry measurement procedure such that a customer can perform optometry measurement. One of a moving image and a still image that indicate the measurement procedure is repeatedly displayed on the monitor until measurement data is obtained.
Each of the optometry apparatuses described in those documents has a function for guiding the person to be examined using a character message or a voice message. Therefore, there is a feature that the person to be examined can (substantially) independently perform examination sequences. The person to be examined operates an input device such as a joystick lever or a cursor key based on the guide to input reply information related to the appearance state of the index to the optometry apparatus. The optometry apparatus performs the selection of a next index to be indicated and the determination of an eyesight value based on the inputted information to automatically advance the subjective examination.
In such an optometry apparatus, when the indicated eyesight chart is switched to another chart, the person to be examined recognizes the measurement is shifted to a next stage. When a beep sound to be outputted in the case where an operational input to the joystick lever is enabled is generated, the person to be examined recognizes the receipt of the reply.
That is, according to such an optometry apparatus, the person to be examined can check the completion of the input operation but cannot check the details of the input operation. For example, assume that the person to be examined recognizes a correct answer “left” about a Landolt ring which is a circle with a left side gap in an eyesight examination using an eyesight chart including Landolt rings and then intends to tilt the joystick lever in a direction corresponding to the “left”. However, when the person to be examined has tilted the joystick lever in a direction corresponding to, for example, an “upper left” by faulty operation, the optometry apparatus determines a “wrong answer” even in the case where the person to be examined has eyesight to check the Landolt ring. When the faulty operation occurs by such an input device, operation for obtaining a correct eyesight value of the eye to be examined requires a redundant time such as a reexamination time. Therefore, an examination time becomes unnecessarily long, with the result that a burden on the person to be examined increases.
Note that only the person to be examined can recognize the faulty operation, so it may be fundamentally impossible that the optometry apparatus actively determines whether or not the faulty operation is performed. Therefore, checking whether or not the faulty operation is performed depends on the recognition of the person to be examined. However, the conventional optometry apparatus cannot cause the person to be examined to check whether or not the faulty operation is performed.
In recent years, Early Treatment Diabetic Retinopathy Study (ETDRS) has improved the diffusion of indices of, a type in which eyesight is indicated based on the logarithm of a visual angle, that is, a log MAR (logarithm of minimum angle of resolution) type. In an eyesight chart of the log MAR type, indices having different sizes at a predetermined rate (10√10) in each of stages of eyesight values are arranged at regular intervals (For example, see “Ophthalmologic Examination Method Handbook (Third Edition)”, Maruo, Koguchi, et al, Igaku-Shoin, 1999, pp. 11 and 12.).
When the eyesight chart of the log MAR type is applied to an optometry apparatus that can perform an examination without depending on an examiner, it is difficult that the person to be examined recognizes a selected index. Therefore, a burden on the person to be examined is large. In addition, examination accuracy is likely to reduce. Those problems occur even in the case of using an eyesight chart for simultaneously indicating a plurality of indices to a person to be examined and then performing an examination while each of the indices is selectively provided to the person to be examined, such as an eyesight chart including a plurality of Landolt rings.
The optometry system disclosed in JP 2002-119471 A includes an optometry apparatus that can perform an examination with depending on the single person to be examined. In order to smoothly perform the examination, training screens for training an input device operating method and an examination procedure are displayed. The training screens are displayed on a monitor device connected with the optometry apparatus through a communication cable. The person to be examined must train while views the training screen on the monitor device provided separately from the optometry apparatus, so that training operation is complicated. When there is no location space, it is hard to locate the monitor device because it is separately provided. In addition, a structure in which the training screens are displayed on a monitor device of a computer terminal for examiner to perform training of input operation is expected. However, when the training operation is to be performed, the assistance of the examiner is required. This becomes a factor of inhibiting automation of an examination process.